Seems like all the major game companies have cloned PUBG. Activision with the new CoD, EA/Dice with Battlefield's upcoming battle royale mode, Epic with Fortnite (no gore and targeting a younger demographic and long since expanded into something a good bit different), and now finally Valve, who presumably took 30% of PUBG's revenue instead of the ~5% Epic were paid, without even providing much of the code, have also cloned it with CS:Go's new Battle Royale.

You can't copyright a game mode, and PUBG took lots of aspects from others too.